A plurality of rollers are provided in conventional printing presses, for example in web-fed rotary printing presses. Inking rollers, in particular, are provided, which are used for transferring the ink from an ink reservoir to the plate cylinders. The ink transferred to the plate cylinders can be metered by the inking rollers, so that the ink is transferred as a uniform film of defined thickness. It is thus possible to even out interferences, such as speed fluctuations and rotary oscillations, for example.
Moreover, dampening unit rollers, which transfer a dampening agent, for example water, to the printing group, can also be provided in the printing press.
Pairs of rollers are often formed by rollers which are in engagement with each other, wherein at least one of the rollers has a cylinder surface made of an elastic material, so that this cylinder surface can be at least slightly deformed as a function of the contact pressure of the oppositely located roller. The result of the elastic deformation of the roller surface is a contact area extending in a straight line between the rollers, which contact area is called a contact strip. The width of the contact strip can be varied by adjusting the contact pressure between the rollers, wherein the width of the contact strip has a considerable effect on the printing result. If, for example, the contact strip in an inking unit is too narrow, not enough ink is transferred, while in the situation in which the contact strip is too broad, the elastic roller can be damaged by the roller's flexing.
In order to be able to adjust the strip width, in particular as a function of the respective operating conditions, for example the temperature of the printing presses, or the degree of their wear, it is necessary to adjustably seat one of the rollers so that it can be pushed in the direction of the opposite roller, by the use of an actuator, with an adjustable force. Once the correct contact pressure between the two rollers has been established, a fixation device, which is usable for fixing the first roller in place relative to the second roller, is actuated in order to maintain the contact pressure permanently.
A device for adjusting the contact pressure between two rollers is known from DE 197 19 305 A1. In the bearing arrangement described there, the adjustably seated roller is pushed against the opposite roller by a spring which is supported on the frame of the printing press. By use of this spring, a defined contact pressure always exists between the two rollers as a function of the respectively selected spring characteristic. A clamping mechanism, with a clamping lever and a clamping plate, is described for fixing the roller in place in the contact position, by the use of which, the roller shaft can be fixed in place against the frame of the printing press by frictional contact.
A device for the semi-automatic adjustment of rollers is known from DE 199 19 733 A1. An adjustably seated roller is maintained in a roller holder, which itself is seated in a frame holder which is arranged fixed in place on the frame. In this case, the roller holder and the frame holder can be displaced with respect to each other and are connected with each other by a spring-elastic assembly. Here the spring-elastic assembly has have a defined pre-tension, so that the roller, which is adjustably seated on the roller holder, can be pressed with a defined contact pressure against the opposite roller. Arresting bolts are provided for arresting the roller holder on the frame holder, because of whose advancement, the roller holder can be clamped with frictional contact to the frame holder.
DE 42 31 873 A1 describes a device for roller adjustment. A roller is initially displaced in the radial direction by the use of a pressure chamber and is subsequently fixed in place.
DD 64 064 describes a device for the fixed clamping of bearing bushes of printing cylinders. No suggestion regarding the adjustment of rollers is provided.
DE 100 01 582 A1 discloses a roller which is displaced by two hydraulic cylinders.